Conventionally, for example, body fluids, etc. (blood, exudates, etc.) are drawn out by retaining the tip of a catheter in the wound of a patient. In this case, the end of the catheter is connected to a suction fluid collector for medical use and body fluids, etc. are removed through suction by operating the suction fluid collector for medical use (for example, cf. Japanese Kokai Patent Application No. Sho 57[1982]8134). Said suction fluid collector for medical use comprises a rectangular plastic bag furnished with a tube connected to the outside and a pair of plates inside and a spring body set between the pair of plates. With this constitution, the suction force generated by the expansion of the plastic bag when the spring is changed from a contracted condition to an extended condition is utilized to suck out body fluids, etc. from the wound of a patient.
The drawback for said conventional suction fluid collector for medical use is that the amount of exudate accumulated in the plastic bag cannot be accurately verified due to the deformation of the plastic bag when the exudate discharged from the body is accumulated in the plastic bag.